This research protect is concerned with the physiology and pharmacology of the neural systems that transmit and modulate pain. The long term goals are to understand the conductance mechanism and the regulation of chemosensitivities of identified dorsal horn projection neurons. The specific projects involve 1) the studies of gating behavior of single calcium channels. 2) the modulation of Ca channels by guanine nucleocides, and 3) the characterization of actions of amino acids, peptides and biogenic amines on these cells. The ionic currents and single channel activities of isolated dorsal horn projection neurons will be measured under voltage clamp conditions. Whole-cell and single channel recording techniques will be used. The knowledge obtained from these experience will greatly increase our understanding of the functional properties of projection neurons and facilitate the designing of better pain therapy.